Just for the game to have a chance of hitting 30fps (and likely still not doing it), they would have to rewrite most of the engine/game code to use ARM cpu instructions, use much lower-poly models with low-res textures and simplified materials, replace all dynamic lighting with static pre-baked, reduce amount of light sources on screen, make the day-night cycle switch between pre-baked times of day (maybe even ditch it completely), remove cloud and sky simulation and replace with static skybox, remove or simplify most shaders, simplify/remove weather system, severely downgrade all particle fx/fog, remove physics based animation, reduce draw distance and LOD, downgrade grass/shrubs/trees, make cutscenes into movie files instead of realtime (like ffxiii), dynamic 900p docked, up to 720p mobile.
